Key Features
This Double Wall THERMOcafe product by Thermos has been designed to keep HOT liquids at drinkable temperatures for up to ONE HOUR and COLD liquids for up to TWO HOURS.
Geniune Thermos Brand VACUUM INSULATED flasks will keep contents hot or cold for several hours, but the contents in TRAVEL MUGS are intended for consumption within and hour or two, so the insulation capabilities have been deliberately modified to allow some of the heat/cold to escape. If normal VACUUM insulation was used, the contents could be too hot to drink with and hour.
It is quite normal to feel some warmth/coolness on the outside of the product because of the above factors.